Various physical phenomena have been analyzed and their practical applications have been found over the years. This document revisits the concept of angular momentum conservation and the corresponding propulsion imparted to a reference frame by an ejected fluid. The focus is on constrained flows within moving frames, where flow confinement results in a well-defined physical problem. The thermophysics of the phenomena are examined with a particular goal in mind—namely, to predict the fluid temperature as observed in different frames of reference, to predict the angular propulsion imparted to the rotating reference frame, as well as describe the underlying physics leading to such observations. Attention is devoted to the applicability of the presented physical model to rotational flows, which exhibit radial temperature separation. A most relevant example is the vortex tube effect, discovered in 1933 by the French physicist Georges J. Ranque. The effect has now been studied for more than 80 years, yet while a number of models have been proposed, they remain a subject of debate. The fundamental reason for this is the complexity of vortex tube flow obscuring the underlying physics, which in its turn obfuscates any concise understanding of the effect. Notwithstanding, interest in the vortex tube phenomena remains high, as demonstrated by a present day literature search in the Google Scholar database resulting in 4240 references to published documents discussing the topic of vortex tube airflow.